1. Field of the Invention
The present invention relates to a water resource treating device and, more particularly, to a water resource treating device for purifying water by removing impurities in the water in a low temperature/low pressure environment.
2. Description of the Related Art
Conventionally, distillation is generally used to separate an easy-to-evaporate liquid from nonvolatile substances, such as seawater desalination or wastewater treatment.
Taking seawater desalination as an example, multi-stage flashing, vapor compression, multi-effect distillation, and reverse osmosis are used to separate seawater into fresh water with a low salt content and brine with a high salt content. FIG. 1 shows a seawater distillation device 9 including a base 91 on which a vacuum pump 92, a water pump unit 93, a vacuum chamber 94, a condensing chamber 95 and a water tank 96 are mounted. The vacuum pump 92 is driven by a windmill 97. The water pump unit 93 includes a suction pipe 931 and a water pump 932. An end of the suction pipe 931 is in the seawater and serves as a suction end. The other end of the suction pipe 931 serves as a vaporizing end. A middle section of the suction pipe 931 includes a first heat-absorbing coil 9311 and a second heat-absorbing coil 9312 wound around the vacuum pump 92. The vacuum chamber 94 receives the vaporizing end of the suction pipe 93. A draining hole 941 is formed in a bottom of the vacuum chamber 94. The condensing chamber 95 receives the first heat-absorbing coil 9311 of the suction pipe 931 and is in communication with the vacuum pump 92 and the vacuum chamber 94. An end of the condensing chamber 95 connected to the vacuum pump 92 serves as an output end in which a filtering net 951 is mounted. A bottom of the condensing chamber 95 is in communication with the water tank 96. An example of such a seawater distillation device 9 is disclosed in Taiwan Utility Model No. M303302.
By sucking seawater through the water pump 932, seawater passes through the suction end to the vaporizing end of the suction pipe 931. Through operation of the vacuum pump 92, each of the condensing chamber 95 and the vacuum chamber 94 forms a low pressure environment to force the seawater preheated by the first and second heat absorbing coils 9311 and 9312 to eject from the vaporizing end of the suction pipe 931. Then, the seawater turns into water vapor with a low salt content through flashing. The water vapor enters the condensing chamber 95 and condenses into fresh water that is stored in the water tank 96. Furthermore, the brine with a high salt content accumulated in the bottom of the vacuum chamber 94 is duly drained via the draining hole 941.
However, a temperature difference is required in the conventional seawater distillation process to achieve the condensation of the water vapor after evapotranspiration of the seawater. Namely, a heat source is required to maintain the temperature difference for continuous flashing of the seawater and subsequent condensation into fresh water. However, the heat source will cause additional energy loss and an increase in the costs. Even though the windmill 97 using the natural wind power is cheaper than conventional electrical devices driven by electricity, operation of the vacuum pump 92 is far less stable than the electrical devices. Thus, the vacuum chamber 94 and the condensing chamber 95 can not maintain the required low pressure environment. As a result, seawater can not easily flash in the vacuum chamber 94. It is not easy to condense a large amount of seawater into fresh water by simply relying on the waste heat of the vacuum pump 92 and the condensing heat of the seawater, leading to low efficiency of seawater desalination.
Thus, a need exists for a novel water resource treating device for seawater desalination or wastewater treatment to continuously proceed with water purification in a stable low temperature/low pressure environment without the above disadvantages.